Classification of biological samples from individuals is not an exact science. In many instances, accurate diagnosis and safe and effective treatment of a disorder depend on being able to discern biological distinctions among cell or tissue samples from a particular area of the body, such as prostate cancer samples and normal prostate samples. The classification of a sample from an individual into particular disease classes has often proven to be difficult, incorrect, or equivocal. Typically, using traditional methods, such as histochemical analyses, immunophenotyping, and cytogenetic analyses, only one or two characteristics of the sample are analyzed to determine the sample's classification. Inaccurate results can lead to incorrect diagnoses and potentially ineffective or harmful treatment.
Prostate cancer (CaP) is the most common non-dermatological cancer in the United States with an estimated 198,100 new cases and 31,500 deaths in 2001. The widespread adoption of screening based upon the serum prostate specific antigen (PSA) level has led to the earlier detection of prostate cancer, with most cases appearing confined to the prostate gland at presentation. While such early diagnosis provides an opportunity to cure men with organ-confined disease, up to 30% of men undergoing radical prostatectomy as primary therapy for such tumors will ultimately relapse, presumably as a result of micro-metastatic disease present at the time of surgery. A critical issue in the care of men with prostate cancer is to improve the risk stratification of patients with intermediate risk disease. Clinical stage, Gleason score, and the serum PSA remain the most important variables with which to predict disease behavior. However, while these measures can successfully distinguish between men at low, intermediate, and high risk for tumor recurrence following local therapy, they are less successful in helping guide therapy for the majority of men falling into the intermediate risk group. Thus, a need exists for accurate and efficient methods for identifying prostate cancer and determining prostate cancer outcomes.